The SCDMA is a broadband wireless access technology of Synchronous Code Division Multiple Access. The SCDMA employs advanced technologies such as smart antenna, software radio, SWAP (Synchronous Wireless Access Protocol) and Air Interface Protocol, and may develop services in the manner of group call. In security solution for air interface of the SCDMA technical standard, a multicast key negotiation method between a user terminal (UT) and a base station (BS) for a group call system is not described.
In consideration of characteristics of the group call system with SCDMA broadband access technology, the generation, updating of the multicast key of a service group and the use of the multicast key after switching group members shall meet the following requirements: 1) the BS does not record a message of the group to which each UT pertains; 2) the BS provides different service groups, and UTs which are served in the same service group may be distributed under different BSs; 3) it is the BS to generate the multicast key of the service group due to it shall have the ability of switching. All group call services in the SCDMA network need to be provided in the manner of multicast, and it will not be guaranteed that the group call services provided by the multicast can be performed more effectively without a secure method and system for the multicast key negotiation.